Tinted glass has been used in a variety of household, commercial, and automotive applications for many decades. Tinted glass helps to reduce the amount of infrared light, visible light, and ultraviolet radiation that is transmitted through transparent glass windows. Tinted windows are typically formed by applying a tinting film to a standard glass window. The composition of the film may vary depending on the desired absorbance of the glass, the size of the glass pane, the thickness of the glass, the construction of the glass window, or the desired application of the glass window.
A recent improvement in tinted window technology is the development of switchable or “dynamic” glass windows. Specifically, coatings on the dynamic glass surface undergo a solid-state reaction when a low voltage is applied to them. The voltage causes a reaction within the coatings, which in turn causes the assembly to darken. The darkened state enables the glass to absorb and reflect heat and glare from the sun. When the voltage is removed, the glass is returned to its clear state, which allows complete absorption of the sun's light.
Transparent conductive coatings are typically applied to the surface of the glass to facilitate electrical conduction. In addition, an electrode formed of an electroconductive paste is typically printed or dispensed around the periphery of the glass to facilitate the flow of electricity to the layered materials. Electroconductive pastes, such as, for example, silver pastes, have traditionally been used to produce these conductive electrodes on glass substrates. An electroconductive paste typically comprises metallic particles, glass frit(s), and an organic vehicle. Once the electroconductive paste is printed or dispensed on the glass, it is typically then fired at an elevated temperature to form the resulting electrode.
The electroconductive paste must adhere well to the glass substrate, and must be able to be fired at relatively low temperatures, to ensure the stability and integrity of the other components. The firing temperature is typically lower (e.g., 300-500° C.) than the firing temperature of electroconductive pastes used in LED, hybrid circuit, and solar cell technology (e.g., 800° C. or above). At such low firing temperatures, achieving adequate adhesion to the glass substrate and low resistivity is difficult. Therefore, an electroconductive paste which has optimal conductive properties, adheres well to a glass substrate, and can be processed at relatively low temperatures, is desired.